This invention relates to facsimile recorders of the type wherein one or more styli carried on a belt traverse a web of recording paper opposite a linear electrode. Electrical signals applied to a stylus and the linear electrode are marked on the recording web as described fully in copending application Ser. No. 755,211, filed Dec. 29, 1976, now U.S. Pat. No. 4,060,815 incorporated herein by reference.
The recorder as described in that application drives the belt on a drive sprocket wheel and an idler roll, both of which are fixed on the recorder frame. However, the recorder of the application would benefit by provision for easier mounting and more constant tension on the belt. A straight forward manner of meeting the two requirements would be by providing a spring loaded, movable idler pulley in place of the fixed idler pulley of the aforementioned application. Such a movable idler pulley belt guide would, however, increase the cost of the recorder by requiring at least a roll with a bearing and some kind of yoke for the bearing as well as a rocker arm for the whole assembly. The movable support for the idler roll would also at least partially obstruct access to the roll to mount the belt, and the drag of the marking stylus produces a slack only behind the stylus which would not be taken up by an idler roll.
It is therefore an object of the invention to provide a more economical form of belt guide, which is easier to manufacture and far simpler to instal in a recorder, which does not obstruct mounting of the belt and which affords uniform tautness around the belt.